(CNN) --The director of the Centers for Disease Control and Prevention said Friday that the influenza outbreak sickening people in three dozen states is an epidemic, though it does not technically meet the definition.

"There is no firm dividing line between what is an epidemic and what is not an epidemic, but I think, when you look at a map that shows widespread influenza activity in 36 states, that we regard it -- from a common-sense perspective -- as an epidemic," Dr. Julie Gerberding told reporters.

Although this year's outbreak began earlier than usual and has spread more widely than usual, Gerberding said it is not clear if the final death toll will exceed the average of 36,000.

The CDC has said more than three-quarters of laboratory-confirmed cases this year are a type of influenza A that is typically associated with severe outbreaks that bring higher hospitalization and death rates.

"But, as we know, the past doesn't always predict the future," she added.

Gerberding added that it is not clear whether the season has peaked.

"It's too soon to tell, but we're hopeful we'll begin to see firm evidence of peaking in the states that were hit earliest on," she said.

So far, 42 children have died of flu-related causes, which Gerberding called "very sobering and worrisome."

Slightly more than half of the children were under 5, and about 40 percent had an underlying medical condition that could have contributed to the death, she said.

"The others either did not or we have not completed the investigation to know whether they did," she said.

Although investigators have determined that several of the children had not been vaccinated, it was not clear how many, she said.

At least three of the children's illnesses were complicated by bacterial infections, she said.

On average, 10-20 percent of Americans can expect to get the flu in any given year, she said. The vast majority get well.

Gerberding urged victims to "self-triage" before seeking care to avoid overwhelming medical facilities. She said breathing trouble, fever that lasts more than four days, a blue tinge to the skin, lethargy or irritability, and seizures are signs that medical attention is needed.

Flu symptoms that resolve and return more forcefully a few days later could indicate a complicating bacterial infection, which she said was "a reason to see a clinician."

People over 65, pregnant women or those with an underlying medical condition such as diabetes or heart disease should also see a doctor, she said.

"If you're in one of those high-risk groups, you should seek care early and not wait."